i have a plastic tug boat kit, and would like to make it a waterline boat to put on dock scene how do you cut off the bottom part of the hull and keep a straight line given the curves and profile of the hull?
I would be willing to try one on a very slow band saw guided by a plate.
I think that I will mask the hull at about the waterline as measured from the keel using a ruler until I get a consistent line and then slowly cut along that tape. After some sanding I would think the model will sit pretty good.
Another way would be to mount a pencil to a peice of material at a height you want the water line to be. Run the pencil along the flat surface next to the hull marking fore to aft. That should provide you with a decent line to follow.
If you have access to a tabletop belt sander, you could put on some fine grit sandpaper and set it down on top of it (holding very firmly). I would draw the waterline first as a guide of course.
Peter
The important thing is to mark an accurate waterline on the model first. Then it is a simple matter of using the cutting tool of your choice ((I use a dremel tool with a cut off disk and a speed controller) and cutting as close as possible to the marked water line. When you are done, even things out with a sanding block.
-George
Have you thought about leaving the boat intact and cutting a hole in your layout base? This would be particularly easy with foam, and probably not so bad even on 3/4-inch plywood.
I’d avoid the belt sander sounds a bit dangerous as the plastic will melt and it could snatch your hand onto the belt and wreck the model too.
Using a flat table or worktop, mount the boat on a small box or some foam so that it sits level as it would in the water, then decide where the waterline is going to be.
Tape a pencil to the top of another appropriate height box so that it marks the hull at your determined level then simply slide the box and pencil around the tug and you’ll have an accurate flat waterline marked.
Use a X-acto saw or similar, or a saw disc in a rotary tool and cut along the line then you can gently sand it flat on a sheet of sandpaper again on a flat surface.
All of the methods above will convert a full-hull model to a waterline model (I personally would rough-cut with a bandsaw, then finish with a belt sander.) The key to realism is what you do next.
If you simply set the model down on already-finished water, there are certain to be unacceptable gaps between the bottom of the model and the troughs of the waves (which will be there, even in ‘smooth’ water.) OTOH, if your model is set into the water, moving it will leave a hull-shaped ‘foundation hole’ in the surf.
One solution I have seen was to model the water, with vessel, as a removable unit (on a tea caddy.) When an empty mooring was desired, the entire water surface was replaced.
All in all, an interesting problem.
Chuck (former A student in Naval Architecture, whose watercourses are navigable - by kayakers living out death wishes)
lay your line first with masking tape and pencil. then assemble the hull with white glue to get a temporary bond. double check your waterline by immersing your model in water. correct any mistake with a sharpie then cut with a razor saw.
An easy way to set the waterline before cutting could be using one of those laser-beam levels found at every hardware store. Just draw a line following the light trace that will be level as long as the beam is horizontal, no matter how curvy the hull is.
Martin
Québec City
OY!
Never thought of that KEWL!!!